1. Technical Field
The invention relates to control arrangements for vehicle transmissions and more particularly to a common shifter interface and communication sub-system for use with automated manual transmission controllers sourced from different manufacturers.
2. Description of the Problem
Manual (standard) transmissions for motor vehicles may be fitted with transmission control modules to provide automated control of the transmission. The transmission control modules (TCMs) or, as they are sometimes called, smart vehicle transmissions, cooperate with a shift controller which provides operator controls and generates electrical signals indicating the operator's choices relating to mode control and gear shift selection exercised through the operator controls. The operator controls may appear conventional, for example a floor mounted gearshift lever may be provided, or they may be less conventional, such as steering wheel mounted buttons. Among the options typically provided the operator are: (1) the ability to select an operating mode, i.e. the operator may shift manually or leave gear selection to the TCM; (2) the ability to request an up or downshift; and (3) the ability to select the operating gear. U.S. Pat. No. 6,151,977 is an illustration of a smart transmission arrangement for a manual transmission. Smart transmissions made by different manufacturers have heretofore required their own unique shift control arrangements. A change in transmission has required either new programming of a transmission controller or new control arrangements. Operator commands to the transmission control modules thus have not been coupled to the TCMs over a data bus such as a controller area network notwithstanding the face that TCMs have typically been fitted for such communication with other vehicle controllers, such as the engine controller and a vehicle body computer (sometimes referred to as the electrical system control module or “ESC”). These systems are typically applied to trucks and other heavy-duty vehicles and differ from transmission for cars where mechanical linkage is used for control of a manual transmission.
Controller area networks (CANs) have proven effective at reducing the number of dedicated communication paths between the numerous switches, sensors, devices and gauges installed on the vehicles, having essentially replaced much of the control wiring of the classical motor vehicle harness with a single twisted pair bus. The widespread adoption of CAN's has been encouraged by the publication by the Society of Automotive Engineers of its SAE J1939 standard. However, shift controllers have not heretofore communicated with transmission control modules over a controller area network, even though transmission control modules have previously been connected to such networks.
The specific manner of implementing multiplexed communications is outside the scope of the present invention, which works within the defined SAE J1939 protocol. Details relating to wiring standards, standardized message formats and types and collision detection and contention access to the bus are well known. The J1939 protocol provides an open protocol, standard message format and definition of the performance requirements of the medium of the physical layer. A controller area network (CAN) may be readily implemented utilizing commercial integrated circuits such as the C167 CAN controller made by Siemens AG of Germany.
Controller area networks can link several digital controllers positioned around a vehicle along with an electrical system controller (ESC) for inter controller communication. Remote digital controllers are not addressed per se, but may be programmed to respond to any signal appearing on the bus to initialize a particular function. Transmission controllers may be a remote digital controller. The controllers may be programmed to allow the device to react to local conditions, signals received over the bus, and combinations of the two sources of data. The ESC may pass requests and instructions received for operations of certain devices, and execute vehicle load management programs.